The incidence of adverse events in the Institute of Medicine's report To Err is Human may underestimate the overall extent of the patient safety problem in the U.S., since injuries occurring after discharge from the hospital were not included. Patients hospitalized for acute medical conditions are often discharged on new medications, with test results that are still pending and with sub-acute medical problems that need to be addressed, but who do not merit further hospitalization. Failure to follow-up on these unresolved medical issues may result in poor outcomes because of delays in diagnosis and treatment. The hospital discharge summary has traditionally been the means through which this information is communicated from the inpatient to the outpatient physician. However, the systems to communicate this information are often sub-optimal, and less than half of all outpatient primary care physicians (PCPs) ever receive their patients' hospital discharge summaries. Discontinuity errors (medication continuity errors, test follow-up errors, and work-up errors) resulting from poor inpatient-to-outpatient communication about patients' discharge plans may occur as often as 50% of the time. [unreadable] [unreadable] The specific aims of the study are to: 1) Conduct a nationally representative survey of hospitals to identify the current systems used to communicate hospital discharge information and their perceived efficacy; 2) Take advantage of a natural experiment to perform an interrupted time series cohort study to measure and compare the frequency of discontinuity errors that occur after hospitalization before and after implementation of a web-based system to disseminate discharge summaries to outpatient PCPs; 3) Assess associations between discontinuity errors (medication continuity errors, test follow-up errors, and work-up errors) and adverse events (readmissions, ED visits, and urgent visits) in this cohort; and 4) Design and evaluate a randomized-controlled trial to compare the effectiveness of an e-mail (active) strategy versus a web-based (passive) strategy of disseminating electronic hospital discharge summaries for reducing rates of discontinuity errors and adverse events. [unreadable] [unreadable]